Change Data Capture (CDC) logging

Change Data Capture (CDC) logging captures changes to data.

Change Data Capture (CDC) logging captures and tracks data that has changed. CDC
logging is configured per table, with limits on the amount of disk space to consume for
storing the CDC logs. CDC logs use the same binary format as the commit log.

Upon
flushing the memtable to disk, CommitLogSegments that contain data for CDC-enabled
tables are moved to the configured cdc_raw
directory. After the disk space limit is reached, CDC-enabled tables reject writes
until space is freed.

CDC directory location

The
location of the CDC directory depends on the
type of installation:

Package installations

/var/lib/cassandra/cdc_raw

Tarball installations

/var/lib/cassandra/cdc_raw

cassandra.yaml

The location of
the cassandra.yaml file depends on the type of
installation:

Package installations

/etc/dse/cassandra/cassandra.yaml

Tarball installations

installation_location/resources/cassandra/conf/cassandra.yaml

Prerequisites

Before enabling CDC logging, define a plan for moving and consuming the CDC log
information. DataStax recommends a physical device for the CDC log that is separate from
the data directories.